<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><br class=""><div><br class=""><blockquote type="cite" class=""><div class="">On 12 Apr 2018, at 13:13, Daniel Menzel <<a href="mailto:daniel.menzel@hhi.fraunhofer.de" class="">daniel.menzel@hhi.fraunhofer.de</a>> wrote:</div><br class="Apple-interchange-newline"><div class="">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" class="">
<div text="#000000" bgcolor="#FFFFFF" class=""><p class="">Hi there,</p><p class="">does anyone have an idea how to decrease a virtual machine's
downtime?</p><p class="">Best<br class="">
Daniel<br class="">
</p>
<br class="">
<div class="moz-cite-prefix">On 06.04.2018 13:34, Daniel Menzel
wrote:<br class="">
</div>
<blockquote type="cite" cite="mid:1c7f3633-258f-0365-443e-6389b77c7ad4@hhi.fraunhofer.de" class="">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" class=""><p class="">Hi Michal,</p><div class=""><br class=""></div></blockquote></div></div></blockquote><div><br class=""></div>Hi Daniel,</div><div>adding Martin to review fencing behavior<br class=""><blockquote type="cite" class=""><div class=""><div text="#000000" bgcolor="#FFFFFF" class=""><blockquote type="cite" cite="mid:1c7f3633-258f-0365-443e-6389b77c7ad4@hhi.fraunhofer.de" class=""><p class="">(sorry for misspelling your name in my first mail).</p><div class=""><br class=""></div></blockquote></div></div></blockquote><br class="">that’s not the reason I’m replying late!:-))</div><div><br class=""><blockquote type="cite" class=""><div class=""><div text="#000000" bgcolor="#FFFFFF" class=""><blockquote type="cite" cite="mid:1c7f3633-258f-0365-443e-6389b77c7ad4@hhi.fraunhofer.de" class=""><p class="">The settings for the VMs are the following (oVirt 4.2):</p>
<ol class="">
<li class="">HA checkbox enabled of course</li>
<li class="">"Target Storage Domain for VM Lease" -> left empty</li></ol></blockquote></div></div></blockquote><div><br class=""></div>if you need faster reactions then try to use VM Leases as well, it won’t make a difference in this case but will help in case of network issues. E.g. if you use iSCSI and the storage connection breaks while host connection still works it would restart the VM in about 80s; otherwise it would take >5 mins. <br class=""><blockquote type="cite" class=""><div class=""><div text="#000000" bgcolor="#FFFFFF" class=""><blockquote type="cite" cite="mid:1c7f3633-258f-0365-443e-6389b77c7ad4@hhi.fraunhofer.de" class=""><ol class="" start="3">
<li class="">"Resume Behavior" -> AUTO_RESUME</li>
<li class="">Priority for Migration -> High<br class="">
</li>
<li class="">"Watchdog Model" -> No-Watchdog</li>
</ol><p class="">For testing we did not kill any VM but the host. So basically
we simulated an instantaneous crash by manually turning the
machine off via IPMI-Interface (not via operating system!) and
ping the guest(s). What happens then?</p>
<ol class="">
<li class="">2-3 seconds after the we press the host's shutdown button we
lose ping contact to the VM(s).</li>
<li class="">After another 20s oVirt changes the host's status to
"connecting", the VM's status is set to a question mark.</li>
<li class="">After ~1:30 the host is flagged to "non responsive”</li></ol></blockquote></div></div></blockquote><div><br class=""></div>that sounds about right. Now fencing action should have been initiated, if you can share the engine logs we can confirm that. IIRC we first try soft fencing - try to ssh to that host, that might take some time to time out I guess. Martin?<br class=""><blockquote type="cite" class=""><div class=""><div text="#000000" bgcolor="#FFFFFF" class=""><blockquote type="cite" cite="mid:1c7f3633-258f-0365-443e-6389b77c7ad4@hhi.fraunhofer.de" class=""><ol class="" start="3"><li class="">
</li>
<li class="">After ~2:10 the host's reboot is initiated by oVirt, 5-10s
later the guest is back online.</li>
</ol><p class="">So, there seems to be one mistake I made in the first mail: The
downtime is "only" 2.5min. But still I think this time can be
decreased as for some services it is still quite a long time.</p><div class=""><br class=""></div></blockquote></div></div></blockquote><div><br class=""></div>these values can be tuned down, but then you may be more susceptible to fencing power cycling a host in case of shorter network outages. It may be ok…depending on your requirements.<br class=""><blockquote type="cite" class=""><div class=""><div text="#000000" bgcolor="#FFFFFF" class=""><blockquote type="cite" cite="mid:1c7f3633-258f-0365-443e-6389b77c7ad4@hhi.fraunhofer.de" class=""><p class="">Best<br class="">
Daniel<br class="">
</p>
<br class="">
<div class="moz-cite-prefix">On 06.04.2018 12:49, Michal Skrivanek
wrote:<br class="">
</div>
<blockquote type="cite" cite="mid:585D25A6-78B5-4416-BA44-7BFE91869077@redhat.com" class="">
<pre wrap="" class=""></pre>
<blockquote type="cite" class="">
<pre wrap="" class="">On 6 Apr 2018, at 12:45, Daniel Menzel <a class="moz-txt-link-rfc2396E" href="mailto:daniel.menzel@hhi.fraunhofer.de" moz-do-not-send="true"><daniel.menzel@hhi.fraunhofer.de></a> wrote:
Hi Michael,
thanks for your mail. Sorry, I forgot to write that. Yes, we have power management and fencing enabled on all hosts. We also tested this and found out that it works perfectly. So this cannot be the reason I guess.
</pre>
</blockquote>
<pre wrap="" class="">Hi Daniel,
ok, then it’s worth looking into details. Can you describe in more detail what happens? What exact settings you’re using for such VM? Are you killing the HE VM or other VMs or both? Would be good to narrow it down a bit and then review the exact flow
Thanks,
michal
</pre>
<blockquote type="cite" class="">
<pre wrap="" class="">Daniel
On 06.04.2018 11:11, Michal Skrivanek wrote:
</pre>
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<blockquote type="cite" class="">
<pre wrap="" class="">On 4 Apr 2018, at 15:36, Daniel Menzel <a class="moz-txt-link-rfc2396E" href="mailto:daniel.menzel@hhi.fraunhofer.de" moz-do-not-send="true"><daniel.menzel@hhi.fraunhofer.de></a> wrote:
Hello,
we're successfully using a setup with 4 Nodes and a replicated Gluster for storage. The engine is self hosted. What we're dealing with at the moment is the high availability: If a node fails (for example simulated by a forced power loss) the engine comes back up online withing ~2min. But guests (having the HA option enabled) come back online only after a very long grace time of ~5min. As we have a reliable network (40 GbE) and reliable servers I think that the default grace times are way too high for us - is there any possibility to change those values?
</pre>
</blockquote>
<pre wrap="" class="">And do you have Power Management(iLO, iDRAC,etc) configured for your hosts? Otherwise we have to resort to relatively long timeouts to make sure the host is really dead
Thanks,
michal
</pre>
<blockquote type="cite" class="">
<pre wrap="" class="">Thanks in advance!
Daniel
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